title: Antifibrillatory efficacy of encainide, loracainide and ORG 6001 compared with lignocaine in isolated hearts of rabbits and guinea-pigs.
abstract: 1 In Langendorff-perfused rabbit hearts, electrical stimulation threshold and ventricular fibrillation threshold (VFT) were measured by applying rectangular impulses of 3 ms duration and increasing current at frequencies of 4 and 20 Hz respectively. 2 Perfusion with lignocaine or one of three new antiarrhythmic drugs, encainide, lorcainide and ORG 6001, produced significant, dose-dependent increases in both thresholds. 3 On a dosage basis, encainide was seven times, lorcainide fourteen times and ORG 6001 twice as potent as lignocaine in raising VFT. 4 In Langendorff-perfused guinea-pig hearts, only lorcainide provided complete protection against ouabain-induced ventricular fibrillation, while 6 of 6, 3 of 6 and 2 of 6 hearts fibrillated in the presence of encainide, lignocaine and ORG 6001 respectively, but with infusion durations significantly higher than control. 5 These results indicate the potential antifibrillatory activity of these new antiarrhythmic agents.
mesh_terms: D000732:Androstanols / Q000494:pharmacology*; D000813:Anilides / Q000494:pharmacology*; D000818:Animals; D000889:Anti-Arrhythmia Agents; D044482:Benzeneacetamides; D016700:Encainide; D005260:Female; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology*; D011817:Rabbits; D013045:Species Specificity
chemical_list: D000732:Androstanols; D000813:Anilides; D000889:Anti-Arrhythmia Agents; D044482:Benzeneacetamides; D010880:Piperidines; D010042:Ouabain; D008012:Lidocaine; C015970:lorcainide; C010158:amafolone; D016700:Encainide